“”In addition to still- and video cameras, amateur "ghostologists" use various other glitch-prone equipment — such as electromagnetic field (EMF) meters — to supposedly detect the energy from ghosts. They breathlessly report "high readings" and "significant spikes" on EMF devices and other equipment. Alas, these ghost buffs are invariably non-scientists, who know little about their devices and what they're really recording, and they do not use scientific protocols and controls. They seem to think that if you use high-tech equipment, they're performing science — but they're actually engaging in pseudoscience. None of the varied instruments they use are designed for ghost detection. There is no scientific evidence that ghosts exist — let alone that they emit electromagnetic radiation or have other detectable properties.

Ghosts are generally defined as "The spirit of a dead person, especially one believed to appear in bodily likeness to living persons or to haunt former habitats."[2] There are two problems with this definition:

Besides ghostly people, there are also ghostly ships (e.g. Flying Dutchman), ghostly planes, a ghostly double decker[3] and enough ghostly pets to open an SPCGA.[4] Some even thought the spooky but natural weather phenomenon of St. Elmo's fire [5] were nature spirits or supernatural omens,[6] however the only truly scary thing was a 1980s film of the same name.

Ghosts are nearly always the product of apophenia (seeing a pattern that in reality doesn't exist)

You die, you're gone. But, your passing may haunt those you leave behind and cause them imaginary experiences of your coming back to… who knows what?

Ghost stories, on the other hand, are a wonderful source of entertainment — but if you decide to make one, be truthful and don't claim it's "based on a true story."[7]

There's also a whole industry devoted to making a fast buck off gullible TV viewers.

It is significant that, just as "UFOs" changed appearance with cultural changes (Bible stories, mystery airships, Close Encounters of the Third Kind etc), ghosts have varied in appearance over time. In the days when bodies were often buried in shrouds, ghosts were reported to be solid, sentient creatures, often dressed in their shrouds, who would meet those who knew them when alive and interact with them. With the advent of photography in the 19th century ghost photos were faked using double exposures. This created the cultural expectation of the transparent apparition, often combined with the earlier shrouded figure to create the "classic ghost". More recently, with advent of the ubiquitous camera phone, photos taken inside dimly-lit buildings or at night will produce "orbs" where the camera flash bounces off dust or insects that pass inside the focal length of the camera and appear blurred and circular. These are claimed to be "spirits" by those too gullible or dim to understand optics. Finally, any glance at "Genuine ghost photos" online will show that Japanese horror movie makeup is now well-known to the unquiet dead, who have adopted that look as their own, sporting black lips, staring eyes, pointy teeth and long, lank black hair no matter what they looked like when alive. Ghostbusters claim there are two main kinds of ghostly hauntings; residual and intelligent.[8] A residual spook is unaware that it's dead, apparently, and will pass through a room, or wash ghostly dishes, without interacting with any living people in the vicinity. An intelligent ghost is the one that makes it into the movies, because they're the ones that know they are dead and are pissed off. This results in them chasing Pac-Man around a mazepoltergeist activity, strange houses in Amityville and Freddie Kruger. Or in a recent notorious Australian case, push some biscuits onto the floor. In either case, almost all ghostly apparitions are "seen" wearing clothing, which may suggest that your clothes have a soul and that they will die when you do.[9]
Ghosts cannot decide whether to haunt the exact location of their death, or the site of their burial, or even just somewhere loosely associated with their life. Thus the Australian gangster Mark "Chopper" Read is said to haunt Pentridge Prison where he served time earlier in his life, rather than where he died or is buried. Ghost Tour guides, normally scientifically rigorous in their research, claim that the ghost of the last man hanged at Boggo Road gaol in Brisbane, Australia, haunts the remaining building, screaming and shrieking, despite the fact that the cell block where he was hanged was demolished years ago, and he wasn't known for loud screams while alive. Of course this free choice for ghosts to haunt pretty much anywhere, not just where they died or were buried, prevents hospitals and graveyards becoming over-run with shrieking apparitions walking through walls, moving furniture, tapping people on the shoulder or making the air turn slightly colder. Such places would become unusable, and we can be thankful that this has not happened.
It is entirely coincidental that many ghostly manifestations exactly reproduce the perceptual phenomena associated with decreased consciousness. These include "things seen out of the corner of the eye", sudden random spoken words or sounds, the sense of being watched, paralysis, the sensation of a light touch on the body, and being "woken" by a "presence". Any resemblance, no matter how exact, to phenomena associated with sleep and the sleep cycle is to be rejected.

Especially around Halloween, newspapers, television and the internets are flooded with supposedly factual ghost stories told from the point of view that ghosts are scary, no conventional explanation for them is likely, and witnesses couldn't possibly be exaggerating or embroidering their accounts. Supporting testimony from scientific-sounding experts can make them seem all the more convincing. In truth, ghost stories are a form of largely formulaic storytelling that historians speculate evolved as a way of dealing with deep-rooted fears of death and dying, possibly inspired by cultural memories of 14th century Black Plague victims wrapped in white sheets. Many of the credulous "true tales" and "eyewitness reports" being published and passed around today are merely modern-day versions of traditional supernatural folklore that has been with us for hundreds of years.[10]

Somehow even weirder is the Stone Tape theory, put forth by archaeologist turned-parapsychologist Thomas Charles Lethbridge, which surmises that ghost phenomena are recordings of traumatic experiences held in rocks instead of being actual entities. No, seriously.

A photograph of a "ghost" haunting Independence Hall, which is definitely not a camera flash. [citation NOT needed]

There is nothing to explain, since there are no consistently observable phenomena to investigate. Hell, even if there was evidence, there isn't really anything that can be used to experiment on such phenomena. Evidence assembled for the existence of ghosts is largely ad hoc, anecdotal and difficult (or impossible) to duplicate or investigate further.

Explanations of ghosts supposedly dodging physical laws (like being semi-transparent or able to pass through walls) date back to Cambridge Platonist Henry Moore in the 17th century who suggested that souls (and therefore ghosts) are essentially four-dimensional beings, an idea that Johann Karl Friedrich Zöllner promoted in the 19th century.[11]

Using Edwin Abbott Abbott's Flatland as his foundation, Carl Sagan in the print version of Cosmos stated:

“”"If a fourth-dimension creature existed it could, in our three-dimensional universe, appear and dematerialize at will, change shape remarkably, pluck us out of locked rooms, and make us appear from nowhere."

—Carl Sagan. Cosmos pg 219

The problem is that most ghost lovers go the easier 'doesn't follow physical laws' route and call it a day. In reality they (though they don't realize it) mean 'doesn't follow three dimensional physical laws'.

Apophenia (seeing meaningful patterns or connections in random or meaningless data) in conjunction with strong emotions can explain many ghost sightings. This combination was used by Carl Sagan to explain the Martian canals seen by Percival Lowell:

“”"There is no doubt that the Mars canals of Percival Lowell were of intelligent origin. The only question is which side of the telescope the intelligence was on. Where we have strong emotions, we're liable to fool ourselves."

—Carl Sagan. Cosmos

Distorted shadows, reflections by not-immediately-obvious fixtures (or the flash of the camera itself), out-of-focus objects (the bug on a lens theory has been used to explain many ghost images in video tapes), and even particularities of the equipment itself coupled to the desire to believe can explain many ghost sightings and even videos of ghosts. A photo taken inside Norwich Cathedral in 2015, purporting to show the ghost of a Bishop, and widely reported in UK tabloids, was in fact a blurry image of a section of wall and one of the timbers supporting the aisle roof. Many such photos exist, where a poor photo causes a misidentification of a background object as a ghost. Were the photo to be sharply focused the illusion would disappear.

Other possible explanations include hallucinations due to a mental disorder or disease.
Another probable explanation could involve the effects of sleep paralysis, especially as many sufferers experience the sensation of being held down by something, sometimes accompanied by terrifying hallucinations.

Belief in ghosts may also come from the refusal to accept the finality of one's own mortality and the possible absence of an afterlife, as well as the inability to cope with the loss of a loved one. Ghosts are, effectively, the "eternal spirit" of someone who has passed from the earthly realm and not finally lodged in heaven (nor hell).

St. Elmo's fire (not that one) may look ghostly to some people, but it is a natural weather phenomenon with a scientific explanation. And one thing it isn't is fire.

Like lightning, St. Elmo's fire is plasma or ionized air that emits a glow. However, it results not from movement of charged particles from a cloud to the ground but rather a corona discharge, caused by an imbalance in electrical charges. This imbalance is between the air and an object around it, and as a tapered surface will discharge at a lower voltage level, it occurs most often on the top of a steeple, mast or plane wing.[12]

Whether or not ghosts exist, it's definitely both dangerous and sinful to try to communicate with them. This is all over the Tanakh, the New Testament, and the Qur'an. And it's especially bad to pay necromancers to help you try. Leviticus 19 doesn't quite say that John Edward is the biggest douche in the universe, but it does say that you'll be "defiled" just by associating with him and those like him. And Deuteronomy 18 makes it clear that he's an abomination—as bad as sacrificing to the wrong god, being gay, or even eating shrimp.[note 3]

But do ghosts exist? Well, the Catholics say we can't be sure,[note 4] and the Mormons give conflicting answers… but most Evangelical Christians, many mainline Protestant churches, and most branches of Islam say no. If you see your departed mother or a famous silent-film star floating through the walls, what you're actually seeing are Satan's evil spirits (for Christians), or djinn (for Muslims), or Cybermen (for Whovians). So, the warnings in the Bible and Quran against talking to ghosts are there for the obvious reason that it's pretty dangerous to try to communicate with a deceitful evil spirit while convincing yourself that it's grandpa. Plus, to most Christians and Muslims, survival after death is bodily resurrection, not floating around as a spirit—or "ectoplasm", whatever that is. That's central to their theology.[note 5] Not every Abrahamic sect agrees, but they mostly have their own reason to doubt ghosts.[note 6][note 7]

And even if ghosts do exist, they definitely aren't haunting houses.[note 8] Or taking care of unfinished business.[note 9] Or helping and/or getting revenge on the living.[note 10] The only reason for ghostly persistence the Bible doesn't explicitly rule out is Whoopi Goldberg sex.

What about the ghosts of Elijah and Moses? Besides the Transfiguration being a bit of a special case, and the fact that Peter would hardly set up tents for a couple of floating blobs of transparent ectoplasm, Elijah never died,[note 11]) so how could he be a ghost?

OK, what about the Witch-King of Endor summoning the dead prophet Samuel for King Saul?[note 12] First, the whole point of the story was to demonstrate how far Saul had fallen, and why God had to kill him and anoint a new King, so he's probably not an example you want to follow, unless you want a very angry Spirit of Elohim to show up and judge you in person. But here are the major explanations:

Evangelical, Calvinist, Anglican, Catholic: Saul was talking to an evil spirit pretending to be Samuel.

↑"Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." Yeah, it doesn't sound as much like an admonition against ghosts as some of the stuff in the Torah or the Epistles, but for some reason it's the verse that Evangelicals usually use against occultists, and it sounds pretty weighty.

↑But we don't have to stone him to death; he's so bad that God will drive him out so we don't have to.

↑Catholic Answers used to say that even trying to answer yes or no would be engaging in occultism.

↑After all, what's the point of Hell without physical bodies to endure the infinite snuff porn?

↑One viewpoint in Judaism, as expressed by Maimonides, is that you actually are non-physical in the afterlife, or at least for the first year—but that means you cannot be seen by the living, and can only communicate with them in dreams, so still no ghosts.

↑Seventh-Day Adventists, Jehovah's Witnesses, and a few others believe you persist as a nonphysical soul after death—but that's because your soul is "asleep" until the resurrection, not running around going "woooooo!"

↑Job 7:9 "… he who goes down to the grave does not come up. He shall never return to his house, Nor shall his place know him anymore."

↑Psalm 146:4: "When his breath departs, he returns to the earth; on that very day his plans perish."

↑Ecclesiastes 9:5-6 "But the dead know nothing, and they have no more reward, For the memory of them is forgotten. Also their love, their hatred, and their envy have now perished; nevermore will they have a share in anything done under the sun."

↑He was called bodily up to Heaven; it's kind of a big deal, especially in Christianity.